Electronic devices such as computer devices and handheld electronic devices may include an antenna to enable them to communicate wirelessly with other devices and communication networks. For example the electric device may have short range communications circuitry to communicate using Wifi (IEEE 802.11) or a similar communication standard and/or long range wireless communications circuitry to communicate using cellular telephone standards such as GSM, EDGE and UMTS etc.
In many countries governments regulate the power at which radio signals can be transmitted by an electronic device. These regulations and power transmission limits vary from country to country and over time. One measure is the Specific Absorption Rate (SAR) which is the rate at which energy is absorbed by a human body exposed to a radio signal. The SAR may be defined as power per mass of tissue and for example measured in Watts per kilogram. The SAR limit may for example be specified as an allowable SAR as measured at a particular distance from the device.